纳米铁基催化剂在CO2加氢制烃中的性能

Properties of the Nano-Particle Fe-Based Catalyst for the Hydrogenation of Carbon Dioxide to Hydrocarbons

使用尿素沉淀凝胶、机械混合和等体积浸渍相结合的方法, 制备了一系列的纳米尺寸FeK-M/γ-Al2O3(M=Cd,Cu)催化剂, 采用扫描电镜(SEM)、透射电镜(TEM)、N2物理吸附、X射线衍射(XRD)光谱和H2程序升温还原(H2-TPR)仪对催化剂进行表征, 并在小型固定床反应器上考察其对 CO2加氢反应的催化性能. 结果表明:3 MPa, 400℃, 3600 h-1, H2/CO2摩尔比为3的条件下, 15%(w, 下同)Fe10%K/γ-Al2O3催化剂可稳定运行100h 以上, CO2转化率为51.3%, C2+烃类的选择性达62.6%. Fe含量降至2.5%时, C2+烃类的选择性仍能达到60.0%. 随着 K 含量由 0%增加至 10%, 低碳烯烃选择性增加, 烯烷比增加至 3.6. Cd 和 Cu 助剂可促进 Fe 物种的还原, 改善目的产物的分布, 其中Cu的加入使低碳产物烯烷比增至5.4, Cd的加入使C5+产物选择性增加了12%.

Combining co-precipitation-gelation, mechanical mixing and impregnation methods, a series of catalysts of FeK-M/γ-Al2O3（M=Cd or Cu） have been attained. The catalysts were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, N2 physisorption, X-ray diffraction （XRD） and temperature-programmed reduction of hydrogen （H2-TPR）. The hydrogenation of carbon dioxide over these catalysts was also investigated in a fixed bed. Given a reaction time of 100 h, CO2 conversion over a 15%Fe/10%K/γ-Al2O3 catalyst reached 51.3 %, with a selectivity towards C2＋ of 62.6 % at 3 MPa, 673 K, a space velocity of 3600 h-1 and at a molar ratio of H2/CO2 of 3. At the lower Fe content of 2.5%, the selectivity towards C2＋ was still greater than 60.0%. Increasing the potassium content from 0% to 10%, increased the selectivity towards C2-C4= and the molar ratio of C2-C4= /C2-C40 increased to 3.6. The addition of Cd and Cu improved the reduction and catalytic activities. Specifically, Cu improved the molar ratio of C2-C4= /C2-C40 from 3.6 to 5.4, and the Cd increased the selectivity of C5＋ by 12%.